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Figure 3-19: One implies a record must be present and zero the record can be present. Identifying and Non-Identifying Relationships Figure 3-20 shows identifying relationships, non-identifying relationships, and dependent tables. These factors are described as follows: . Identifying relationship The child table is partially identified by the parent table, and partially dependent on the parent table. The parent table primary key is included in the primary key of the child table. In Figure 3-20, the COAUTHOR table includes both the AUTHOR and PUBLICATION primary keys in the COAUTHOR primary key as a composite of the two parent table fields. . Non-identifying relationship The child table is not dependent on the parent table such that the child table includes the parent table primary key as a foreign key, but not as part of the child table s primary key. Figure 3-20 shows a non-identifying relationship between the AUTHOR and PUBLICATION tables where the PUBLICATION table contains the AUTHOR_ID primary key field from the AUTHOR table. However, the AUTHOR_ID field is not part of the primary key in the PUBLICATION table. . Dependent entity or table The COAUTHOR table is dependent on the AUTHOR and PUBLICATION tables. A dependent table exists for a table with an identifying relationship to a parent table. . Non-dependent entity or table This is the opposite of a dependent table. 198711905 345308999 345306275 345438353 553278398 553293362 553293370 553293389 893402095 1585670081 5557076654 1150 1200 1800 2000 1900 1050 1950 1100 1850 1000 1250 130 140 ISBN RANK INGRAM_UNITS Rank Edition 198711905 246118318 345308999 345323440 345333926 345334787 345336275 345338353 449208133 553278398 553293362 1150 1200 1800 2000 1900 1050 1950 1100 1850 1000 1250 ISBN RANK INGRAM_UNITS 553293370 553293389 893402095 1585670081 5553673224 5557076654 Hardcover Hardcover Paperback Paperback Paperback Paperback Paperback Paperback Hardcover AudioCassette AudioCassette Non-highlighted editions do not have rankings 57 Database Modeling Building Blocks
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